(1) Field of the Invention
The production of fibrous webs or sheets of paper or paperboard in which the present invention is concerned with submerged rolls and other submerged rotating and fixed elements, all arranged and operated in a different and unique fashion.
(2) Description of the Prior Art
In the manufacture of paper, the presence of static electrical charges on the cellulosic fibers and on particles of clay and other filler materials, including residual resins, are regarded as the primary cause for such fibers to flocculate, i.e., cling together or clot, forming "bundles" which are detrimental to the paper's formation, water removal (including drying), appearance and function of the final marketable paper product.
Minimizing flocculation has been the objective of many patented devices, one of these being Beck U.S. Pat. No. 3,597,818 patented Aug. 1971, where holes in rectifier rolls (a.k.a. "holey" rolls, mixing rolls, etc.) are drilled/honed, e.g., to a flared streamlined form through the wall of the roll shell. Beck's idea was to align the outward-flowing fibers into equally-spaced, parallel paths as they exit the roll downstream to the slice, a spout-like member depositing the fibrous slurry onto the forming wire of the papermaking machine.
Another example is Skoldkvist U.S. Pat. No. 3,694,312 patented Sept. 1972, an attempt to cure or alleviate flocculation by two separate and distinctive devices: means to intermittently introduce the fibrous suspension into the headbox, thereby creating a pulsating flow into the box above the area where the slurry enters the box, some distance, fortunately, from the slice; pulsations not dampened out before entering the slice are reflected in the newly-forming paperweb as ripples or waves that, at best, lower sheet quality, but often cause rejection of such flawed paper.
Skoldkvist's second anti-floccing device, in the same patent, comprises stiring rods radiating outward from a central, driven shaft, three rod-sets, each set positioned to keep slurry agitated as it progresses from the pulsating inlet into the slice.
Yet another is Evalahti U.S. Pat. No. 3,674,633 patented July 1972, a mechano-electrical drive device for maintaining a constant, or fixed, position of the rectifier roll relative to the movable front slice plate. The idea is to retain the roll's intimate clearance with the upper and lower slice plate. The claims cover several power sources to move the roll in conjunction with the movement of the slice plate.
Then there is the "family" of patents termed the "bunched tube" concept to anti-flocculation, the forerunner of these being Showers U.S. Pat. No. 2,688,276 patented Sept. 1954. Later members of the family are: Burgess et al U.S. Pat. No. 3,328,236 June 1967, Notbohm U.S. Pat. No. 2,328,237 June 1967, and Notbohm 3,528,882 Sept. 1970, that stand out among others. The concept employs a multiplicity of small-bore tubes, or other small cross sections, running closed-spaced in parallel, the tube bundles converging into the mouth of the slice, the bundle usually preceded by a standard rectifier roll. Supplemental flow straighteners are also covered by the same patents.